Guy Ferland's "The Babysitter," at first glance, looks like the sort of “erotic thriller” you usually leave on the shelf — the unrated sizzlers with titles like "Sexual Malice" or "Sensual Obsession" or "Fatal Nookie."

And the appearance of Alicia Silverstone in the lead role further leads you to expect a rehash of The Crush, with Alicia as the damsel in distress rather than the psycho-bitch. Finally, whatever synopsis you might read should kill your interest: Psychological thriller about an innocent babysitter who becomes the focus of men’s dangerous fantasies. Oh, please.

Prepare for a surprise. The Babysitter is a complex chiller with the best witty-sinister fantasy sequences this side of Brian De Palma (only without De Palma’s mocking cartoonishness). Silverstone is the Babysitter (she’s not named until the very end), who’s taking care of a little boy and girl for the night. The kids’ father (J.T. Walsh), who still harbors adolescent fantasies of bagging babes in the back seat and really misses those days, takes one look at Silverstone and quietly goes insane.

“Quietly” is the key: The father goes to a party with his dissatisfied wife (Lee Garlington) and can’t stop daydreaming about coming home to discover the wide-eyed babysitter all sudsy in his bathtub, asking him to soap her back.... Giving himself over to these giddy mind-movies (photographed by Rick Bota in creamy pinks), the always-fascinating J.T. Walsh is deeply funny; he’s like a horny little pudge who can’t wait to be alone so he can gawk at his hidden copy of Playboy. (His pre-pubescent son has a collection of nudie photos, too, and nurtures his own soapy dreams of the babysitter.) Walsh keeps trying to get away from the party, which suits his wife fine, because she’s busy getting drunk and fantasizing about the host.

Meanwhile, the babysitter’s mild-mannered ex-boyfriend (Jeremy London) and his bad-news buddy (Nicky Katt) wander around town, debating whether London should visit the girl and make a move. Katt, who briefly dated her, taunts London with hints about what he’s missing. All the while, their own babysitter fantasies bloom: London’s are tender Blue Lagoon affairs, while Katt’s involve red-light roughness. The boys’ friendship starts off intriguing (they’ve had some falling-out) and then deepens; Guy Ferland lets them talk, get on each other’s nerves and back off, and we feel they share experiences we don’t know about. Nobody in the movie is cardboard: London is more than just a straight-arrow, Katt is more than just a punk, and Walsh is more than just a horndog. Ferland’s joke is that the babysitter is both more and less than what the men are making her out to be in their dream-worlds, and he deliberately doesn’t give her a past, parents, or even a name. She’s an object of fantasy, yet whenever she opens her mouth in real life she says something that explodes the fantasy.

Ferland doesn’t shy away from the ticklish naughtiness of the fantasies. We giggle at the foolishness of J.T. Walsh imagining himself joining Silverstone in the bathtub fully clothed, yet we also recognize that fantasies often are ridiculous. (De Palma understood that, as did Buñuel and David Lynch.) The fantasies seem fine-tuned, perfected in the minds of the men through repetition; they play like authentic masturbation scenarios. And Ferland keeps cutting back to the babysitter, blissfully unaware of all this erotic attention. But then the naughtiness gradually turns nasty, as it’s meant to. Ferland is saying that the objectification essential to male fantasy inevitably leads to dehumanization, and from there to cruelty. The men converge on the house, now intent on playing out their fantasies, and the tone of the movie shifts from erotic to suffocating and, I thought, rather upsetting.

The Babysitter isn’t overly explicit; Silverstone never appears nude. (Ferland slyly interrupts the men’s fantasies before they cross the line into hardcore.) But it does get at something dark and wormy in American masculinity. It uses the horror-movie convention of the vulnerable, virginal babysitter (as seen in Halloween) to illuminate what many men really want, and the picture isn’t pretty. Does Ferland objectify Alicia Silverstone to dramatize her objectification? He has to, I think; apart from denying the men the sex they want, she has little personality. But outside the male fantasies, Ferland doesn’t fetishize Silverstone the way Alan Shapiro did in The Crush, turning her into a lethal Lolita. She’s just an ordinary girl trying to control two unruly kids (who keep jumping on her and tickling her — further unwanted physical attention). In the fantasies, though, when the babysitter is usually giggly or submissive, Silverstone shows some wit. And Ferland directs Silverstone to play two distinct types of fear: the no-means-yes type that the babysitter shows in the men’s later rape fantasies, and the real thing — genuine shock and alarm at these boys-of-all-ages who have lost the ability to distinguish fantasy from reality.

I realize why Ferland shoots the works in the climax — he needs the violence to release the tension that’s been building. But it still feels too movie-ish, an intrusion of fantasy on reality. It’s worth noting, though, that the only ones who get hurt are the men. This, too, feels unreal and contrived but symbolically right.

In real life, of course, women are too often raped and killed by men like these, who can’t control their aggressions, their self-disgust expressed as hatred of women. But in the end, the men stand baffled by what their thoughts have led to. “What were you thinking?” the babysitter asks London, who can’t answer. We can, though. "The Babysitter" gets under your skin and stays there.